This invention relates generally to improvements in a roof pin used for mine or tunnel roof support, and more particularly to an improved pin assembly that effectively grips the roof strata under support load upon insertion into a compatible pin hole.
The majority of the heretofore conventional types of pins utilize an expansion shell for gripping the roof strata. When utilizing this type of roof pin, the roof pin and expansion shell are inserted into a drilled hole in the roof strata to the desired depth. When fully inserted, the pin, which is in fact a bolt, is turned to expand the expansion shell blades outwardly into gripping relation with the roof strata. With this particular roof pin, the expansion shell must be maintained in the location desired while at the same time the shell blades must be manually expanded.